Photographic emulsions containing symmetrical tetranuclear dye salts



April 8, 1952 Filed Oct. 31, 1950 Fig. I.

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L. PHOTOGRAPHIC EMULSIONS CONTAINING SYMMETRICAL c. HENSLEY 2,592,515

TETRANUCLEAR DYE SALTS' 2 SHEETS-SHEET l EMULSION OGITAINING DYE SALT OFEXAMPLE I EMULSION CONTAINING DYE SALT OF EXAMPLE II 4o 44 4a 52 56 so64 ea EMULSION CONTAINING DYE SALT OF EXAMPLE Ill EMULSION CONTAININGDYE SALT OF EXAMPLE IV INVENTOR Lee C. Hensley A; iORNEYS April 8, 1952Filed Oct. 31, 1950 Fig. 5.

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L. C. HENSLEY PHOTOGRAPHIC EMULSIONS CONTAINING SYMMETRICAL TETRANUCLEARDYE SALTS 2 SHEETS SHEET 2 EMULSION CONTAINING DYE SALT OF EXAMPLE VEMULSION CONTAINING DYE SALT OF EXAMPLE VI EMULSION CONTAINING DYE SALTOF EXAMPLE VII EWLSION CONTAINING DYE SALT OF EXAMPLE VIII INVENTOR LeeC. Hensley BY) Lgw Patented Apr. 8, 1952 PHOTOGRAPHIC EMULSIONSCONTAINING SYMMETRICAL TETRANUCLE AR DYE SALTS Lee C. Hensley,BinghamtomN. Y., assignor to General Aniline & Film Corporation, NewYork, N. Y., a corporation of Delaware Application October 31, 1950,Serial No. 193,284

6 Claims. (01. 95-1) This invention relates to gelatino silver halideemulsions. and particularly to photographic emulsions sensitized bymeans of new symmetrical tetranuclear dye salts in which the centralnucleus, 4,4'-bithiazole, is linked to two heterocyclic nitrogenousnuclei by a mono or polymethine chain.

The use of sensitizing dyes, particularly in multilayer color film,poses many problems. It is known that sensitizing dyes operate by dyeingthe silver halide grain. To do this, they must be adsorbed to the silverhalide. If they are displaced from the silver halide grains, they losetheir effectiveness as sensitizers. It is also known that many colorformers used in color photography have greater aflinity for silverhalides than the sensitizers, and act to displace the same from thesilver halide grains. One must, therefore, select a sensitizer whichwill not be so displaced.

Another problem arises as regards the migration ofthe sensitizers fromone emulsion to another. Where this ensues, color distortion is theinevitable result. Many proposals have been made dealing with theanchoring of compounds in silver halide emulsions, the most noteworthybeing the use oi a long alkyl chain (see Wilmanns et al. United StatesPatent 2,186,849).

It is, therefore, necessary, when providing sensitizers, particularlyfor color photography, to make certain that they have (1) the propersensitizing power, (2) the ability to withstand displacement from silverhalide grains by color formers, and (3) the ability to resist diffusionfrom one sensitized emulsion to another.

Efiorts which satisfy the last prerequisite, uniortunately; often leadto compounds which will not meet the first two tests. -Thus, it is knownthat the sensitizing power of cyanine dyes varies with the substituenton the cyanine N-atoms. Where this substituent is alkyl, the powerdecreases as the chain length increases. Hence, it a long alkyl chain beused to anchor the dye in the emulsion, we end up with aproduct oflittle or no sensitizing power- The use of other expedients to anchorthe dye, on the other hand,

and

Y often gives products incapable oi withstanding on nc t t thedisplacement action of color formers insofar as the silver halide grainsare concerned. It is thus manifest that the provision of sensitizershaving the necessary prerequisite is a difficult problem, to say theleast. It is known that many cyanine dyes sensitize photographic silverhalide emulsions to high red sensitivity. Most of these dyes, however,are not suitable for sensitizing silver halide emulsions containingcolor coupling components. This is thought to be due to a physicaldisplacement which the sensitizing dye undergoes when color couplingcomponents are added. That is. the sensitizer is adsorbed to the surfaceof the silver halide grain, and then with addition of color couplingcomponent, is displaced therefrom.

An object of the present invention is to provide photographic silverhalide emulsions with new symmetrical tetranuclear dyes containing a4,4- bithiazole nucleus. I

A further object is to provide such dyes which are free from thedisadvantages noted above.

Other objects and advantages of this invention will become apparent byreference to the following specification in which its preferred detailsand embodiments are described.

This invention is predicated upon the discovery that symmetricaltetranuclear dye salts, in which the central nucleus, 4,4'-bithiazole,is linked to two heterocyclic nitrogenous nuclei by a mono orpolymethine chain, are not only sensitizers for orthochromatic andpancromatic film emulsions but are also compatible with color couplingcomponents, being unaffected by the presence of color couplingcomponents and exhibiting the property of non-migration from the layerin which they are incorporated. In the latter combination, thesensitizing action of the dye salts is not impaired or diminished. Anadditional advantage of these dye salts is their ability to remain fixedin the layer in which they are originally. deposited.

The symmetrical tetranuclear dyestuffs i'ulfilling the above advantagesare characterized by the following general formulae:

whereinR is an alkyl or aralkyl group, e. g., methyl, ethyl, propyl,butyl, amyl, etc, benzyl, phenethyl and the like, R1 and R2 are eitherhydrogen or an alkyl group, e. g., methyl, ethyl.

propyl, butyl, and the like, R1 being'only hydrogen when n equals 1, Xrepresents an anionic acid radical, e. g., Cl, Br, I, C104, SO iCHg,804021-15, SO3C5H4CH3. and the like, Z represents the atoms necessary tocomplete a 5- or'fi-membered nitrogenous heterocyclic system of the typeusual in cyanine dyes, such as pyridine, lepidine, quinoline, indoline,oxazole, thiazoline, thiazole, thiodiazole, pyrroline, selenazole,selenazoline, oxazoline, benzothiazole, benzoselenazole, benzoxazole,naphthothiazole, perinaphthiazole, naphthoselenazile, and the like, andn represents a positive integer ranging from I to 2.

The process of preparing the above tetranuclear cyanine dyes comprisescondensing by gentle'heating or boiling, or by heating as on a steambath or under reflux conditions, one mol of adiquaternary cyclammoniumsaltof 2,2'-dimethyl-4,4- bithiazole with two mols of a cyclammoniumquaternary cyanine dye intermediate of the type used in the preparationof cyanine dyes. This condensation is carried out in the presence of anacid binding agent, such as nitrogenous heterocyclic base containing asmall quantity of a tertiary base which may include a small quantity ofacetic acid or acetic anhydried. The anions of the dye salts thusobtained are readily converted into different anions by methods wellknown in the art.

The diquaternary cyclammonium salts of 2,2- dimethyl-4,4'-bithiazoleutilized in the condensation reaction are characterized by the followinggeneral formula:

HaC-C wherein R and X have the same values as above, and are obtained byvquaternizing 2,2'-dimethyl- 4,4-bithiazole characterized by thefollowing formula': 4

The 2,2-dimethyl-4,4-bithiazole is prepared in the following manner:

Eight and six-tenths grams (0.1 mol) of butanedione-2,3 (diacetyl) in 35cc. of carbon disulfide were treated dropwise with stirring, with asolution of 10.6 cc. of bromine in 20 cc. of carbon disulfide at theboiling point ofthe carbon disulfide. The addition was completed in 3hours.

' water bath under increased pressure in the usual The stirring andheating were continued another 2 hours. After cooling,the carbondisulfide was decanted from the solid which had separated. The crystalswere washed with petroleum ether (B. P. 60-75 C.). The melting point ofthe crude product was 109-111 C. After crystallizing from petroleumether (B. P. Gil-75 C.), the melting point was 117 C. and the yield ofthe product was 13.6 grams.

One gram of 1,4-dibromobutanedione-2,3 and 0.63 gram of thioacetamidewere dissolved in 20 cc. of absolute methanol and warmed for 10 minuteson the steam bath. The mixture (a solid had separated) was poured into100 cc. of water. The

manner. The alkylating agent employed may be methyl or ethyl iodide,dimethyl sulfate, methyl p-toluenesulfonate, phenethyl iodide, and thelike. The cyclammonium salts of the type used or proposed for theproductionof cyanine dyes, and utilized in accordance with the presentinvention may be any one of those having an appropriate group in thereactive position to the nitrogen atom thereof. As examples of suitablecyclammonium quaternary cyanine dye salt intermediates having a reactivegroup in the 2-position to the nitrogen atom thereof so as to form adirnonomethine dye, the following may be mentioned:

2-methylmercapto-6methylquinoline ethiodide 2-methylmercaptopyridineethiodide 2-methylmercaptothiazoline ethiodideZ-phenylmercaptothiazoline ethiodide, and the like.

In preparing straight chain di-trimethine cyanine dye salts and branchedchain di-trimethine dye salts, the following cyclammonium quaternary dyesalt intermediates having a reactive group in the pi-position of theside chain in the 2-position of the nitrogen atom thereofmay beemployed:

Z-(B-acetanilidovinyl) thiazoline ethiodide 2 (p-acetanilidovinyl)benzothiazole ethiodide 2- (B-acetanilidovinyl) benzoxazole ethiodide 2(/3 ethyl-fl-methylmercaptophenyl) -5-methoxy-benzoselenazole ethiodide2 (fl-methylmercapto-B-methylvinyl)benzothiazole ethiodide 2(p-methylmercapto-;9-propylvinyl) benzothiazole ethiodide.

In preparing straight chain or branched dipentamethine anddiheptamethine cyanine dye salts, the following cyclammonium, quaternarysalts having a reactive group in delta and zetapositions of thesidechain in 2 -position of the nitrogen atom thereof may be employed:

2 (4-acetanilido-1,3-butadienyl) pyridine ethiodide 2- (4 acetanilido1,3 butadienyhbenzoxazole ethiodide 2-(4-ethoxy 1,3 butadienyDpyridineethiodide 2 (4 anilino-3-methyl-1,3-butadienyl)pyridine ethiodide2-(4-anilino-3-methyl-1,3-butadienyl) -/3 naphthoxazole ethiodide 52-(4-anilino-3-ethyl-l,3 butadienyl) a naphthothiazole ethiodide 2(6-anilino-1,3,5 -hexatrienyl) thiazoline ethiodide2-(6-anilino-1,3,5-hexatrieny1) -a naphthothiazole ethiodide2-(6-anilino 1,3,5 hexatrienyl) 5 naphthothiazole ethiodide 2-(6-anilino 1,3,5- hexatrienyl) a. naphthoselenazole ethiodide 2-(6-anilino 1,3,5 hexatrienyl) B naphthaselenazole ethiodide'2-(6eanilino-4-methyl-l,3,5 -liexatrienyl)thiazoamount oi methanol andcrystallized from pyriline ethiodide dine. 2-(6-ani1ino-4-methyl-1,3,5-hexatrienyl) benzo- The purified product has a melting point ofthiazole ethiodide 245-,-246 C. A methanol solution of the dye-2--(6-anilino-4-butyl 1,3,5 hexatrienyl) benzo- 5 showed an absorptionmaximum at 497 mi. The thiazole ethiodide. dye sensitized a silverbromoiodide emulsion The above cyclammomum (mammary dye salt from 450 mto 5'70 m, with a sensitivity maxiintermediates are well known to theart and mum 540 hence the methods for their preparation need Example IISe, CH s s C Se\ I i I 6 v. -0

c-cn= z-.cn=o E H H g o-on=d-cn=o 0 crno- 0cm v v v. I I 11m 271B; (1335v Ali H 21' not be discussed herein. While the above dye Fifty-fivehundredths gram of 2,2-dime thylintermediates are disclosed'as being inthe form 4,4'-bi.thiazole di-(ethyl ptoluenesulfonate) was of thepreferred ethiodide, it is to be underdissolved in cc. of methanol withslight warmstoodthat they may also be employed in the ing. To thismixture 8 drops of triethylamine form of other quaternary saltspreviously menwere added. After 2 to 3 minutes, 1.1 grams of tioned. 2(p-ethyl-p-methylmercaptovinyl) -5-methoxy,- In the preparation of thesenew symmetrical benzoselenazole'ethiodide were added and thetetranuclear dyestuffs, the '2,2'-dimethyl-4,4'-bimixture gently boiledfor 10 minutes. After coolthiazole base is converted into thecorrespond- 25 ing the reaction mixture, 25 cc. of 10% aqueous ing alkylor aralkyl quaternary cyclammonium potassium iodide solution were addedwith stirsalt in the manner usual with the conversion ring. Afterstanding a short time, the solid was of other nitrogenous heterocyclicbases to the filtered oif and: washed with ether. The crude quaternarysalt form. As previously pointed out, dye was digested in 50 cc. of anequal mixture of .this may be effected by fusion with alkyl or methanoland isopropanol'. After standing overaralkyl halide or by heating thebase with an alkyl night, the dye was filtered off and recrystallize oraralkyl halide in a sealed tube in a water bath from the methanol; underincreased pressure. A molecular equiva- Th yield of the dye Ob ained w.47 ram lent of the quaternary salt thus obtained is heatwith a meltingp0 2 C- A m h nol ed with two molecular equivalents of thecyclarnsolution of the dye showed an absorption maxi-- rnonium cyaninedye salt intermediate in the mum at 5'71 mu. h y sensitized a lv rpresence of a condensing agent, such as a heterobromoiodide emulsionfrom 500 m to 655 m cyclic nitrogenous base or an alcohol containingwith a sensitivit maximum at 620 m/ a small quantity of a tertiary baseat reflux temperature Example As condensing agents employed in the prep-0 s s aration of the new dyes of the present invention, the followingmay be advantageously em- Hi0 C-CH=CH-CH=C ployedz. heterocyclicnitrogenous bases, such as pyridine, methylpyridine, dimethylpyridine,ethv 0 N N ylpyridine, ethylmethylpyridine, trimethylpyri- 12115 dim21-. dine, quinoline and the like, or an alcohol, such as methyl, ethyl,propyl, isopropyl, butyl, iso- One gram. of z-(p-acetanilidovinyl)-5.6-

butyl, and the like, in the presence of a basicmethylenedioxybenzothiazole ethiodide. .6 gram tertiary catalyst, suchas trimethylamine, triof 2.2- m y '-b l Dr 1u ethylamine, and the like..enesulfonate),j 25 cc. of pyridine. and 1 cc. of The following examplesdescribe in detail the triethylaminewere gently boiled for 15.,minutes.methods for accomplishing the above objects, After cooling. two volumesof dilute aqueous but it is to be understood that they are insertedpotassium iodide were added; The solid was merely for the purpose ofillustration and are so filtered oil and washed with water and then notto be construed as limiting the scope of the ether. The product waspurified by (1) digestinvention. ing with isopropanol, (2) digestingwith an equal Example I mixture of methanol and isopropanol, (3)digest,-

OHP s s cm \CH H0/ cn=c g g 0-41-02! N N |H| N I I N afil IHI xHl 21'Seven tenths gram of 2-methylmercapto-6- ing with methanol. The mixturewas allowedto methylquinoline ethiodide and 0.6 gram of 2,2'- cool eachtime before the product was filtered o'if. dimethyl-4,4'-bithiazoledi-(ethyl p-toluenesul- The weight of the final product was 0.45, gramfonate) in 8 cc. of methanol containing 0.5 cc. of 1 with a meltingpoint of 249-259 C. A methanol triethylamine were gently heated untilmethylsolution of the dye showed an absorption maximercaptan ceased tobe evolved. After standing mum at 600 mi. The dye sensitized a silverseveral hours, the solid was filtered by suction. bromoiodide emulsionfrom 520 my to 670 mi, The dye was purified by boiling with a small 7;with a sensitivity at 640 m ape-again Example IV Fifty-six hundredthsgram of 2,3-dihydro-3- ethyl-5,6-methylenedioxy 2thioacetonylidenebenzothiazole, v1 gram of methyl p-toluenesulf onate,and 0.3 gramof 2,2-dimethyl-'4,4-bithiazole di-(ethylp-toluenesulfonate) were warmed gently in a. free flame with stirringfor 4-5 minutes. Five cc. of methanol were added and themixture boileduntil about half of the methanol had boiled. off. Twenty-five cc. ofpyridine and 15. drops of triethylamine were added and the mixtureboiled for 5 minutes. After cooling, 100 cc. of a potassium iodidesolution were added to the reaction solution with stirring. Themixturewas allowed to'stand 3 hours, the product filtered off and airdried. The dye was digested with 70 cc. of isopropanol. After cooling,the solid wasfiltered off, dissolved in 150 cc. of hot methanol,filtered while hot, and the filtrate evaporated to about 70 cc. Theaddition of about one-half volume of ether caused the dye to separate asa powder. The yield of the finalv dye'was 0.13 gram having ameltingpoint of '267-263" C. A methanol solution of the dye showed anabsorption maximum at 5'13 m t- The dye sensitized a silver bromoiodideemulsion irom 500 m to 645 m with a sensitivity-maximum at 620 m l.

Example V Five tenths gram of 2-(,8-acetanilidovinyl)-4,5-benzobenzothiazole methiodide and 0.3 gram of2,2-dimethyl-4,4'-bithiazole di-(ethyl p-toluenesulfonate) in 10.cc. ofpyridine containing 10 drops of triethylamine were stirred at roomtemperature for 5 minutes and then. gently boiled for 5 minutes; Aftertooling,v the reaction mixture was diluted with 25 cc. of a 10% aqueoussolution of potassium iodide. After an hour, the product was filteredoff and washed with water and then ether. .15 minutes with 40 cc. ofisopropanol. After cooling;v the product was filtered off and redigestedtwice with 40 cc. portions of methanol.

The yield of the purified dye was 0.3 gram with a melting point of236-237" C. A methanol solu- Example VI S C 'rn him that A 21-Forty-five hundredths gram of 2,2f-dimethyl- 1 4,4'-bithiazole di-(ethylp-toluenesulfonate) and The product was digested for ity maximum'at 610mp.

Example -v11 Eighty-seven hundredths gram of 2-(fi-a'cetanilidovinyllbenzoxazole ethiodide and 0.6 gram of 2,2-'dimethyl-4,4"bithiazol'e di ethiodide were dissolved in 30 cc. of methanol and warmedon a steam bath for 15 minutes'in the presence of 10 drops oftriethylamine. Five drops of a 40% aqueous solution of sodiumperchlorate" were added and the mixture warmed another 15 minutes. Aftercooling, the crystals were filtereciofi and recrystallized frommethanol.

' The crystallized dye has a melting point of 273- 274 C. Amethanolsolution'of. the dyeshowed an absorption maximum at 532mu. Thedye sensitized a silver bromoiodide emulsion from 460 m l to 605m with asensitivity maximum at Example VIII One andiifteen-hundredthsgram ofZ-(t-acetanilidobutadienyllbenzoxazole ethiodide', 0.98 gram of2,2-dimethyl-4,4-bithiazole di-(phenoxyethyl p-toluenesulfonate), and 8drops of triethylamine were stirred for 5 minutes at room temperature in6 cc. of pyridine. The solution was then gently boiled for 4 minutes.After cooling, the dye was precipitated by adding- 2 volumes of a- 20%aqueous potassium iodide solution. The

' productwas dissolved in methanol and precipitated by the addition of asmall amount of water. The dye after being crystallized twice frommethanol melted at 193-195 C.

. The absorption maximum. in methanol is 613 m The sensitization maximumin a silver iodobromide-emulsion is at 665 me with the sensitivity rangeextending from'540 my to 700m In the'preparation of emulsions containingthese-tetranuclear cyanine dyes, the dye may be dissolved inmethyl orethyl alcohol and the a1- coholic; solution containing from 5 to 50milligrams of the dye added to a liter oi emulsion.

, I l9 10 While in general practicer it may not be nees- I'erredprocedures, materials, and uses; it is v to'ibe sary to add the dyeiii-amounts larger than'tho'se understood that the new classes oftetranuclear above given, generally, for satisfactory results, cyan nedyes and th ir us as s sit z n yes is amounts ranging from to 25milligrams are notlimited thereto and numerous variations and sufficientto obtain the maximum sensitizing e'fmodifications may be made, as rple. his feet. However, I do. not-wish 'to limit my invencondensing thediquaternary; ammonium salt of tion to thequantities just indicatedxasthe most 2,2-dimeth yl-4,4'-bithiazole with a dialkylamisuitable amountwill in each case befourid by: a nobenzene in the presence of abasicrcondensirig few comparative experiments. The dyes may be agents 8-p p y y dye a e obadded to theemulsion in the form of solutions. tained.Accordingly, it is intended'that the iri- Suitable solvents'y asindicated in the examples, vention be defined only by the accompanyingare the alcohols, for instance, methyl or ethyl alclaims. cohol. whichmay be anhydrous" or diluted with a I claim: small volume of water. Inactual practice, the l. A photographic gelatino silver halide emuldyesare applied to the emulsion during any stage sion which contains adyestuff characterized by of its production. However, they arepreferably the formula selected from the class consisting of added tothe finished emulsion before coating. the following formulae:

and

Th r ic spectrogram o s i u i g wherein R represents a member selectedfrom the the accompanying. drawing illustrate the regions classconsisting of alkyl and aralkyl groups. R1 of th p tr m o which some f tr and R2 represent members selected from the class nuclear cyanine dyeswill sensitize a gelatino consisting of hydrogen and alky1groups,R1being silver halide emulsion containing about 4-5% of only hydrogen whenn equals 1. n represents a silver halide and the extent of thesensitization positive integer ranging from 1 to 2, X represents atvarious wavelengths. Figures 1 to 8 of this an anionic radical, and Zrepresents the atoms drawing illustrate the sensitizing properties ofnecessary to complete a member of the group the dyes prepared inaccordance with Examples consisting of 5- and G-membered nitrogenous 1to 8, respectively. heterocyclic ring system.

This application is a continuation-in-part of my 2. A photographicgelatino silver halide emulapplication Serial No. 92,584, filed May 11,1949, sion which contains a dyestuff of the following now abandoned,which was a division of applica- 5 structure:

3. A photographic gelatino silver halide emultion Serial No. 67, 075,filed Decembei 23, 1948. now abandoned. The sensitizing dyestuffs per se3123 3 22 contains dyestufi of the following s s 89 o-on=i on=o FF Eo-on=i on=c cmo- \N N/ V \N 0011,

recl'mdina l' g z Eamon serial No 193 283 filed 4. A photographicgelatino silver halide emul- While the present invention has beendescribed sion which contains dyestufi of the following in considerabledetail with respect to certain prestructure:

P5; A phot ogl-aphic elitinosilver halide=-emuI-.- '36. .A photographicgelatinp silvqnhalldp @1911]- :s ipn which contains ;a 'dyestufl of thefollowing s1onwhich gontains "a dye'atufl 0! the vfollowing structure: 7structure: I

LEE C. No references .cited.

1. A PHOTOGRAPHIC GELATION SILVER HALIDE EMULSION WHICH CONTAINS ADYESTUFF CHARACTERIZED BY